<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    var num=10
    alert(num.toString());  //"10"
    alert(num.toString(2));  //"1010"
    alert(num.toString(8));  //"12"
    alert(num.toString(16))  //"a"
</script>
</html>